1. Field of the Invention
The present invention relates to a water pump drive mechanism for use with an evaporative cooler, and more particularly to such a mechanism for installation in conventional evaporative coolers for driving water pumps employed therein from a blower pulley utilized therewith.
2. Description of the Prior Art
Evaporative coolers, in which air is cooled by evaporation of water into the air to provide comfort in hot weather, are well known. Such coolers are particularly effective in relatively dry climates. Such coolers conventionally include a box-like enclosure, the lower portion of which is supplied with water so as to maintain a predetermined level. Certain of the walls are provided with pads containing fibrous material which is moistened with water drawn from the lower portion of the enclosure. The water is delivered by a small pump through conduits to the top of the pads and runs downwardly thereof wetting the fibrous material with any excess returning to the lower portion of the enclosure. Such coolers frequently contain a power driven squirrel cage blower within the enclosure. The blower draws the relatively hot, dry ambient air through the pads where a portion of the water evaporates cooling the air and increasing its humidity. The cooled and humidified air is delivered from the blower through a duct extending therefrom to a location to be maintained at a comfortable temperature below that of the ambient air.
In such evaporative coolers, the water pump and the blower are rotationally driven by electric motors individual thereto. The blower has a shaft extending therefrom and provided with a pulley of relatively large diameter. The blower motor is customarily mounted upwardly of the blower with an output shaft extending parallel to the blower shaft. A relatively small pulley is mounted on the motor shaft in alignment with the larger pulley. An endless belt links the pulleys so that the blower is rotationally driven by the motor.
The water pump has a vertical drive shaft with a rotor secured to the lower end thereof below the level of the water. The pump has a casing enclosing the rotor and extending upwardly from the water in circumscribing relation to the vertical shaft. The casing and shaft extend upwardly from the water to the electric motor of the pump. The output shaft of the motor is an extension of the pump drive shaft and the motor is secured to the top of the casing so that the pump and motor form a single unit. The casing has feet extending concentrically therefrom which rest on the bottom of the enclosure. This water pump and motor unit is not connected to the balance of the evaporative cooler except for flexible electricity and water connections. The pump has only to raise the limited amount of water required to wet the pads to the top thereof, a few feet at the most.
As can be realized from the preceding description, the water pump motor is located in an extremely disadvantageous location for electrical equipment. At best, this motor constantly is exposed to the humid atmosphere within the enclosure. Since the motor is positioned toward the bottom of the cooler adjacent to the water level, the motor is subject to drips from pads or defective water conduits or to being submerged if knocked over during careless maintenance. As a result, the life of such motors is relatively short due to electrical and corrosion problems associated with the wet environment. The motors, therefore, frequently must be replaced during the life of an evaporative cooler at a substantial expense.
The water pump motor, even though relatively inexpensively constructed, is a significant portion of the cost of an evaporative cooler since such a cooler is a relatively simple device. Such a motor, being of fractional horse power due to the low head and limited flow of water required, is relatively expensive for the power developed. Such motors are frequently inefficient electrically due to their small size and economically oriented design.
The blower motors are more expensive than the water pump motors due to the higher power required by the blower. However, these motors are not as subject to damage from the wet environment since they are securely mounted toward the top of the enclosure away from the wettest conditions near the water level. The blower motors being of larger size are more efficient and can be of better construction than the water pump motors.